• Archives of Pharmacal Research
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• v.20 no.4
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• pp.324-329
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• 1997

AB-type amphiphilic copolymers (abbreviated as LE) composed of poly (L-leucine) (PLL) as the A component and poly (ethylene oxide) (PEO) as the B component were synthesized by the ring-opening polymerization of L-leucine N-carboxy-anhydride initiated by methoxy polyoxyethylene amine $(Me-PEO-NH_2)$ and characterized. Core-shell type nanoparticles were prepared by the diafiltration method. Particle size distribution obtained by dynamic light scattering was dependent on PLL composition and the size for LE-1, LE-2 and LE-3 was $369.6{\pm}267$, $523.4{\pm}410$ and $561.2{\pm}364 nm$, respectively. Shapes of the nanoparticies observed by transmission electron microscope (TEM) were almostly spherical. The critical micelle concentration (CMC) of the nanoparticles determined by a fluorescence probe technique was dependent on the composition of hydrophobic PLL, and the CMC for LE-1, LE-2 and LE-3 was $2.0{\times}10^{-6},1.7{\times}10^{-6}$ and $1.5{\times}10^{-6}(mol/l) $, respectively. Clonazepam release from core-shell type nanoparticles in vitro was dependent on PLL composition and drug loading content.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.52.2-52.2
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• 2011

Flat form technology for constructing anticancer loaded multi-walled carbon nanotubes (mwCNTs) was introduced in this study. Conventional anticancer drugs, such as MTX (Methotrexate), cisplatin, DOX (Doxorubicin hydrochloride), DAU (Daunorubicin) and EPI (epirubicin) were bio-conjugated with folic acid (FA) for selective targeting tumor cells. Loading efficiencies of the used anticancer drugs on mwCNTs have shown different order of bindings depending on the molecular bind affinity of NH (amine) formation on mwCNTs. MTT assays have shown increased selective target efficiency of FA conjugated mwCNTs on breast cancer cell growth inhibition. All results collectively indicated promising application of mwCNTs as a smart inorganic nanomaterial for selective targeting drug delivery vehicle at tumor tissues.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.2
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• pp.170-180
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• 2017

An autoinjector allows a single use medical device serving for automatic intramuscular injection to deliver a dose of a particular emergency drug through an intuitive activation mechanism. By design and structure, autoinjectors are easy to use and are intended for self-administration by patients or untrained personnel. Depending on the number of drugs filled in the cartridge, autoinjectors are divided by one-chamber type and multi-chamber type. Most autoinjectors may have a special structure including spring-loading syringes and needle which is specially designed to ensure strength due to the necessity of penetration through layers of clothing. The purpose of this study was to introduce the design technology of autoinjector of multi-chamber type that could be released into the two drugs sequentially. Additionally, we verified performance of the prototype developed by applying the design.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1579-1584
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• 2002

Since surfactant or emulsifiers remained on the nanoparticle surface significantly affect the physicochemical properties, the biodegradation rate, the biodistribution, and the biocompatibility of nanoparticles, surfactant-free nanoparticles should be good candidate. surfactant-free PLGA nanoparticles were successfully prepared by both the dialysis method and the solvent diffusion method. The PLGA nanoparticles prepared using the solvent diffusion method has a smaller particle size than the dialysis method. The solvent diffusion method was better for a higher loading efficiency than the dialysis method but the nanoparticle yield was lower. Testosterone (TST) release from the PLGA nanoparticles was dependent on the particle size rather than the drug contents. Testosterone release from the PLGA nanoparticles prepared by the solvent diffusion method using acetone was faster than those prepared by the dialysis method. TST release from the PLGA nanoparticles prepared by the solvent diffusion method using acetone and the dialysis method using dimethylformamide (DMF) was completed for 4 days while the PLGA nanoparticles prepared by the dialysis method using acetone showed approximately 80% TST release after 4 days. Since the PLGA nanoparticle degradation ratio was below 20% within 5 days at all samples while TST release completed within 4 days, TST release was dependent on the diffusion mechanism rather than degradation.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.62-70
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• 2005

The nanoindenter and AFM have been used for nanofabrication, such as nanolithography, nanowriting, and nanopatterning, as well as measurement of mechanical properties and surface topology. Nanoscale indents can be used as cells for molecular electronics and drug delivery, slots for integration into nanodevices, and defects for tailoring the structure and properties. Therefore, it is very important to make indents of desired morphology (shape, size and depth). Indents of different shapes can be obtained by using indenters of different geometries such as a cube comer and conical and spherical tips. The depth and size of indents can be controlled by making indentations at different indentation loads. However, in case of viscoplastic viscoelastic materials such as polymethylmethacrylate (PMMA) the time dependent deformation (TDD) should also be considered. In this study, the effect of process parameters such as loading rate and hold-time at peak load on the indent morphology (maximum penetration depth, elastic recovery, transient creep recovery, residual depth pile-up height) of PMMA were studied for hyperfine pattern fabrication.

• The Korean Journal of Food And Nutrition
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• v.25 no.2
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• pp.239-245
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• 2012

The inhibitory activities of a water extract of Sanghwang mushroom(Phellinus linteusau)(SWE) against ${\alpha}$-glucosidases were evaluated in this study. Inhibiting these enzymes involved in the absorption of disaccharides significantly decreases the postprandial increase in blood glucose level after a mixed carbohydrate diet. Oxygen radical absorbance capacity and 1,1-diphenyl-2-picryl hydrazyl scavenging activities of the SWE were evaluated to investigate the antioxidant activity of the SWE associated with complications of long-term diabetes. Furthermore, the postprandial blood glucose lowering effect of SWE was compared to a known type 2 diabetes drug($Acarbose^{(R)}$) in a Sprague-Dawley rat model. SWE significantly reduced the blood glucose increase after sucrose loading. These results suggest that SWE, which has high ${\alpha}$-glucosidase inhibitory activity and high antioxidant activities, has the potential to contribute to a useful dietary strategy for controlling postprandial hyperglycemia.

• Macromolecular Research
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• v.17 no.7
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• pp.538-543
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• 2009

In this study, methotrexate (MTX)-encapsulated polymeric micelles using methoxy poly(ethylene glycol) (MPEG)-grafted chitosan (ChitoPEG) copolymer were prepared. The MIX-incorporated polymeric micelles of ChitoPEG copolymer has a particle size of around 50-100 nm. In 1H nuclear magnetic resonance (NMR) study, the specific peaks of MTX disappeared in heavy water ($D_2O$) and only the specific peak of MPEG was observed, while all of the peaks were confirmed in dimethyl sulfoxide (DMSO). These results indicated that MTX was complexed with chitosan and then formed an ion complex inner-core of the polymeric micelle in an aqueous environment. The drug contents of the polymeric micelle were around $4{\sim}12%$ and the loading efficiency of MTX in the polymeric micelles was higher than 60% (w/w) for all of the formulations. The cytotoxicity of MIX and MTX-incorporated polymeric micelle against CT26 tumor cells was not significantly changed.

• Journal of Biomedical Engineering Research
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• v.39 no.4
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• pp.147-152
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• 2018

Lung cancer and pulmonary metastasis are the leading cause of cancer mortality worldwide. Survival for patients with lung metastases is about 5%. Nanoparticles have been developed for the imaging and treatment of various cancers, including pulmonary malignancies. In this work, we report lipid coated polymeric nanoparticles (LPNs) with an average diameter of 154 nm. In vivo performance of LPNs was characterized using optical imaging system. We expect this nanoparticle can be used for finding lung cancer or lung metastasis. Eventually loading therapeutic drug with the nanoparticle will be utilized for cancer diagnosis and effective therapy at the same time.

• Archives of Pharmacal Research
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• v.10 no.2
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• pp.88-93
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• 1987

Chitosan ($\beta$-D-glucosaminan) is chemically prepared from chitin (N-acetyl-$\beta$- D-glucosaminan) which is an unutilized natural resource. We now report on the suitability of the chitosan matrix for use as vehicles for the controlled release of drugs. Salicylic acid and aspirin were used as model drugs in this study. The permeation of salicylic acid in the chitosan membranes was determined in a glass diffusion cell with two compartments of equal volume. Drug release studies on the devices were conducted in a beaker containing 5% sodium hydroxide solution. Partition coefficient (Kd) value for acetate membrane (472) is much greater than that for fluoro-perchlorate chitosan membrane (282). Higher Kd value for acetate chitosan membrane appears to be inconsisstent with the bulk salicylic acid concentration. The permeability constants of fluoro-perchlorate and acetate chisotan membranes for salicylic acid were 3.139 ${\times}10^{-7}cm^2$ min up to 60 min and that of 30% aspirin in the devices was 4.739${\times}10^{-7}cm^2$sec upto 60 min. As the loading dose of aspirin in a chitosan device increased, water up-take of chitosan device increased, but in case of salicylic acid it decreased. The release rate increased with increase in the molecular volume of the drugs. Thses result suggest that the release mechanism may be controlled mainly by diffusion through pores.

• Macromolecular Research
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• v.11 no.1
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• pp.2-8
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• 2003

The self-assembly of polymers can lead to supramolecular systems and is related to the their functions of material and life sciences. In this article, self-assembly of Langmuir-Blodgett (LB) films, polymer micelles, and polymeric nanoparticles, and their biomedical applications are described. LB surfaces with a well-ordered and layered structure adhered more cells including platelet, hepatocyte, and fibroblast than the cast surfaces with microphase-separated domains. Extensive morphologic changes were observed in LB surface-adhered cells compared to the cast films. Amphiphilic block copolymers, consisting of poly(${\gamma}$-benzyl L-glutamate) (PBLG) as the hydrophobic part and poly(ethylene oxide) (PEO) [or poly(N-isopropylacrylamide) (PNIPAAm)] as the hydrophilic one, can self-assemble in water to form nanoparticles presumed to be composed of the hydrophilic shell and hydrophobic core. The release characteristics of hydrophobic drugs from these polymeric nanoparticles were dependent on the drug loading contents and chain length of the hydrophobic part of the copolymers. Achiral hydrophobic merocyanine dyes (MDs) were self-assembled in copolymeric nanoparticles, which provided a chiral microenvironment as red-shifted aggregates, and the circular dichroism (CD) of MD was induced in the self-assembled copolymeric nanoparticles.